Method for embossing plastic material



Patented May 24, 1932 UNITED STATES PATENr ROLAND G. ANDERSON, or NEWT-HAVEN, CONNECTICUT, AssrGNon., BY MEsNE AssIGN- MENTS, TO THE GCODYEARS INDIA. RUBBER GLOVE MANUFACTURING COMPA OF NAUGATUCK, CONNECTICUTVA COEPDRATION OF CONNECTICUT- METHOD FOR EMBOSSING- PLASTIC MATERIAL Application led October 18,l 1927. Serial N0. 227,000. Y

canized vrubber with indicia such as trademarks, sizes, etc., a common practice has been to use an ordinary stamp which forms a recessed mark in the stock. An objection to this is that the mark tends to fill up, by reason of returnflow of the rubber, and in the case of varnished articles the varnish also assists in filling up the recess. 1t has also been proposed to form an embossed mark by the use of cooperating male and female dies on opposite sides of the rubber stock, but owing to the elastic nature of the material it does not flow suciently if light pressure is used, resulting in al blurred and poor mark. If a heavy pressure is used the rubber tends to squeeze out from between the dies with resultant thinning and weakening of the stock over the area of th-e impression. Moreover there is a recess onone side of the stock corresponding to each embossed or raised portion on the opposite side. When such an embossed pieceof stock is plied up in making an article air is entra-pped in the recesses, and in the subsequent vulcanizing operation blisters form at these points and the articles are ruined or must b-e sold as seconds.

It is an object of this invention to emboss unvulcanized rubber without leaving the imprint of theY edges of the face of the die in the rubber. It is a further object to form characters such as figures and letters pro* jecting from the rubber which shall project outwardly to a considerable extent and be sharply defined. It is a further object to provide an embossing die which when used in embossing rubber will leave an emblem projecting from the rubber'over its entire area and not merely in outline. Other objects will be apparent from the specification and from the accompanying drawings in which latter:

Fig. 1 is a plan View of the die;

Fig. 2 is a side section of the die along the line 22 of Fig. l; Y

Fig. 3 is a front section of the die'alongthe u line 3-3 of Fig. l; and

F ig. 4 is a fragmentary section along the line 4 4 of Fig. l;

Referringparticularly tothe drawings,the;l5 Y

die comprises' a bodyv portion provided with an embossing face l in 4which there is provided a continuous recess 2 which extends around the face in spaced relation to the edges thereof. The face is progressively inset '#60 from the cuter edge of the `recess 2 to the edge of the face as indicated at 3. Recesses t in the shape of characters ysuch as figures or letters are formed inthe embossing face of the die and the portion of the face bearing these-35 characters is made substantially flat, as is clearly shown in Figs. 2 and 8. The recesses 2 and 4 are preferably formed at least twice as deep as their width at any portion thereof and the walls of the recesses are formed @zo almost perpendicular to the surface, preferably inclined approximately 2o outwardly from perpendicular. y'When the walls are inclined substantially less than 2o the rubber will not readily strip from the die, while'-'w when the angle is made appreciably larger the embossed portions are not sharply defined. `When emblems of considerable area are to'be formed in the embossingldie the portion of i ythe face of the die surrounding the emblem-Bo Yis; projected outwardly fromthe 'die as is shown ati forming a raised extension. projecting from the face of the die with a 'concave' curvature. Into th'eprojecting portion j of the facethere is cut the rece'ssvG, the walls?"85 of which extend in the outlines of the emblem @to be formed, asfor examplean elephants head as illustrated in the drawings. The recess is cut deeply into the face of the die to; a

.f depth sufficient to provide the desired heght; -z

to the embossing, and the outer walls of the Vrecess are slightly inclined outwardly from theV perpendicular, the precise angle depending somewhat on the size and shape of then areeffectedby forming recesses within..the?" trici?. l

' tion of the base between the wall 7 and the Wall of the recess in a generally convex shape. By virtue of this construction when the die is pressed against aV sheet of rubber the rub- -ber will tend to flow sharply into the recesses at the base of these walls making the outlines of the area particularly sharply defined in the rubber. Similarly other features of the die such as the eye 8, the wrinkles 9, 10 and 11, and the tusks 12 are formed by providing recesses in the die at the desired locations. As a consequence Ywhen embossing with this die the prominent convex portions of the die adjacent the eye, tusks and wrinkles tend to force the rubber sharply into the recesses leaving portions of rubber constituting these parts 'projecting sharply from the surrounding rubber.

In utilizing the vdie for embossing sheets of rubberstock of a thickness approximate ly {6-3/8 or greater', the die is pressed against the surface of the sheet, preferably With a. yielding pressure of approximately 500 lbs. in two separate impulses. The die .cooperates with a backing or support for the rubber of unbroken outline, no male die being` used. By the use of a yielding pressure a good impression can be obtained on stocks varying, considerably in thickness Without the necessity of positively adjusting the stroke of the die. When first applied the die sinks into the rubber and the rubber flows laterally vfrom the portion opposite the solid v portion of the die and into the recesses of the die with considerable velocity sufiicient to force the rubber far beyond the limit of its natural stretch and sufficient to cause the rubber to become expanded by its own in* ertia. After the first impulse the movement of the die Vis momentarily slowed down or halted, and `it then continues to the end of its stroke. The entire operation is very rapid, occupying only about one'half a second, and'during the first impulse the flow of rubber into the recesses tends to lag.

into the recesses to the proper extent, and the final impulse substantially fixes or sets the rubber in its embossed position.

, elasticity of the rubber, however, it tends to recede slightly from its highest position when the pressure on the die is relieved, but

by reason of the deep embossing recesses it has flowed into the recesses -suiiiciently far so that upon settling back to4 assume its final set condition, it will still extend deeply into the die. The die tends to break down the Thek momentary halt permits4 the rubber to flow bearing the emblem of enlarged area first embosses the rubber, causing the prominent part of the 'design to stand out clearly in sharp outlines from the face of the sheet of rubber. The outer recess 2 not only in effeet forms an embossed outline or frame for the main emblem but it also tends to prevent How of rubber to the outside of the die outline. The pressure of the die adjacent the characters irons out the surrounding` rubber so that the vcharacters project outwardly prominently.

It is obvious'that the above characteristics hold good when the embossing recesses are of other shapes than in the specific embodiment shown. l

Havin' thus described my invention, what I claim and desire to protect by Letters Patent is:

l. The method of lezxjnbossing,unvulcanized rubber which comprises Asubjectin'g the rubber to a rapid and yielding heavy pressure in successive impulses between a female die and an unbroken supporting surface.

2. The method of embossing unvulcanized rubber which comprises subjecting the rubber to a yielding pressure of substantially 50() lbs. in successive impulses between a female die and an unbroken supporting surtace.

Sign-ed at yNew Haven, county of New Haven, State of Connecticut, this 12th day ol Gctober, 1927. 'Y y ROLAND Gr. ANDERSON.

Due to the L grain structure of the rubber and due to the l f sharpness of the angle at which the recesses are cut the outlines of the projecting portions of the rubber are sharply defined.Y As the Adie passes into the rubber the portion thereof 

